I find this idea that, just because you are in a public place, you cannot act privately, rather hilarious. Granted, it would be stupid to say something secret you wouldn't want broadcast to the world, in the middle of a crowd, while someone is speaking...but is it really unreasonable to expect to be left alone when all you want to do, is to turn your head to your coworker, and say some sort of wisecrack?
I have been to many conferences, and have, many times, told something to someone that I thought might have been funny. While I don't think I have ever said something that I would think was harmful I nonetheless have said things that I would be embarrassed of they went "public", because I simply would not have wanted to be the focus of the attention.
I have read Adrian's blogpost, and she doesn't give enough detail for me to know just what it was about the comments that was offensive. Whether they were or not, I don't think it's unreasonable to expect that the two developers were expecting their conversation to be quasi-private.